Study On The Nutrient Absorption Characteristics Of Yam And Its Optimal Fertilizer Practice

This study was conducted in Lixian county of Baoding city, the main production areaof yam in Hebei province. The current fertilization status and existed problems of yamwere firstly investigated by the method of face-to-face interviews with filling questionnaire,and then the development characters, nutrient requirements of yam and its optimalfertilizer rates and distribution were studied by field experiment. Finally, a series of fieldregional test were conducted to verify the reasonable fertilizer practice. The main resultswere shown as follows:1. The survey results showed that more than95%farmers chronically appliedpotassium sulfate and diammonium phosphate as basal fertilizer, meantime,80%farmersalso used organic fertilizer as basal fertilizer. It also showed that80%surveyed farmersmostly used compound fertilizer as topdressing, about35%farmers used trace elementfertilizer,20%farmers applied biofertilizer, and only5%surveyed farmers used urea andammonium bicarbonate as topdressing, respectively. The phenomenon of super-applyingfertilizers was common, and the ratio of N, P₂O₅and K₂O was not match with the nutrientdemand characteristics of yam.2. The experiment of NPK optimum dosages showed that, with the applying amountof NPK increasing, the yam yield obviously increased firstly and then decreased, whichconfirmed that the relationship between yam yield and input of N, P conformed to the lawof diminishing returns. Based on the result of fitted equation of fertilizer amounts and yamyield, considered the comprehensive situations of soil texture, the variation of soil fertilityand the nutrient demands characteristics of yam, the preferred fertilization plan of yam was270³30kg N/hm²,180²25kg P₂O₅/hm², and285³45kg K₂O/hm², respectively.3. The experiment results of yam’s growth and development showed that the keyfactor that assured high-yield of yam and high-efficient absorption of nutrient was to applyN, P and K fertilizers reasonably. If anyone of N, P and K deficiency appeared, the drymatter accumulation of yam, the nutrients accumulation and utilization were all influencedmore or less. Nitrogen was the major limited factor for yam growth, K was the next, and Pwas the least.4. The results of regulation and distribution of nitrogen and potassium showed that nitrification inhibitor remarkably improved nitrogen utilization of yam and appeared someincreasing effect on yam yield. When the N ratio of basal fertilizer to three topdressingswas2:2:3:3, no significant differences were found in nutrient accumulation and yamyield compared with those under the condition of4:2:2:2nitrogen operation model.The similar results were also obtained between the two K ratio of6:4and6:2:2ofbasal fertilizer to topdressing. Considered the poor capacity of water and nutrientconservation of sandy or sandy-loam soil, the low nutrient demand at the early growthstage of yam and the high demand on K at the later growth stage,2:2:3:3of Noperation model and6:2:2of K operation model were recommended as the reasonablefertilization way. The amounts of demanded nutritents for producing1000kg yam were3.65⁴.58kg N,0.82¹.06kg P₂O₅and4.20⁴.74kg K₂O, respectively. The proportion ofN, P₂O₅and K₂O was1:0.18⁰.29:0.98¹.15.